AbstractIn addition to containing higher concentrations of organics and bacterial cells, surface waters are often more vulnerable to pollution and microbial contamination with intensive industrial and agricultural activities frequently occurring in areas surrounding the water source. Therefore, surface waters typically require additional treatment, where the choice of treatment strategy is critical for water quality. Using 16S rRNA gene profiling, this study provides a unique opportunity to simultaneously investigate and compare two drinking water treatment plants and their corresponding distribution systems. The two treatment plants treat similar surface waters, from the same river system, with the same sequential treatment strategies. Here, the impact of treatment and distribution on the microbial community within and between each system was compared over an eight-month sampling campaign. Overall, reproducible spatial and temporal dynamics within both DWTPs and their corresponding DWDSs were observed. Although source waters showed some dissimilarity in microbial community structure and composition, pre-disinfection treatments (i.e. coagulation, flocculation, sedimentation and filtration) resulted in highly similar microbial communities between the filter effluent samples. This indicated that the same treatments resulted in the development of similar microbial communities. Conversely, post-disinfection (i.e. chlorination and chloramination) resulted in increased dissimilarity between disinfected samples from the two systems, showing alternative responses of the microbial community to disinfection. Lastly, it was observed that within the distribution system the same dominant taxa were selected where samples increased in similarity with increased residence time. Although, differences were found between the two systems, overall treatment and distribution had a similar impact on the microbial community in each system. This study therefore provides valuable information on the impact of treatment and distribution on the drinking water microbiome.HighlightsSource waters show some dissimilarity in microbial community.Treatment processes increases similarity and selects for the same dominant taxa.Differential response to chlorination causing increased dissimilarity and variation.Stabilisation of DWDS microbial community through selection of same dominant taxa.Microbial community dynamics are reproducible between the two systems.
Reproducible Microbial Community Dynamics of Two Drinking Water Systems Treating Similar Source Waters
